An MRI scan uses magnets and radio waves to capture images inside your body without making a surgical incision. The scan allows your doctor to see the soft tissue of your body, like muscles and organs, in addition to your bones.
An MRI can be performed on any part of your body. A lumbar MRI specifically examines the lumbar section of your spine — the region where back problems commonly originate.
The lumbosacral spine is made up of the five lumbar vertebral bones (L1 thru L5), the sacrum (the bony “shield” at the bottom of your spine), and the coccyx (tailbone). The lumbosacral spine also consists of large blood vessels, nerves, tendons, ligaments, and cartilage.
Your doctor may recommend an MRI to better diagnose or treat problems with your spine. Injury-related pain, disease, infection, or other factors could be causing your condition. Your doctor might order a lumbar MRI if you have the following symptoms:
- back pain accompanied by fever
- birth defects affecting your spine
- injury to your lower spine
- persistent or severe lower back pain
- multiple sclerosis
- problems with your bladder
- signs of brain or spinal cancer
- weakness, numbness, or other problems with your legs
Your doctor might also order a lumbar MRI if you’re scheduled for spinal surgery. The lumbar MRI will help them plan the procedure before making an incision.
An MRI scan provides a different kind of image from other imaging tests like X-rays, ultrasound, or CT scans. An MRI of the lumbar spine shows the bones, disks, spinal cord, and the spaces between the vertebral bones where nerves pass through.
Unlike an X-ray or CT scan, an MRI doesn’t use ionizing radiation. It’s considered a safer alternative, especially for pregnant women and growing children. Although there are sometimes side effects, they’re extremely rare. To date, here have been no documented side effects from the radio waves and magnets used in the scan.
There are risks for people who have implants containing metal. The magnets used in an MRI can result in problems with pacemakers or cause implanted screws or pins to shift in your body.
Another complication is an allergic reaction to contrast dye. During some MRI examinations, contrast dye is injected into the bloodstream to give a clearer image of blood vessels in the area being scanned. The most common type of contrast dye is gadolinium. Allergic reactions to the dye are often mild and easy to control with medication. But, sometimes anaphylactic reactions (and even deaths) can occur.
Before the test, tell your doctor if you have a pacemaker. Your doctor may suggest another method for inspecting your lumbar spine, such as a CT scan, depending on the type of pacemaker. But some pacemaker models can be reprogrammed before an MRI so they’re not disrupted during the scan.
You doctor will ask you to remove all jewelry and piercings and change into a hospital gown before the scan. An MRI uses magnets that can sometimes attract metals. Be sure to tell your doctor if you have any metal implants or if any of the following items are present in your body:
- artificial heart valves
- prosthetic joints or limbs
If your doctor uses contrast dye, tell them about any allergies you have or allergic reactions you’ve had.
If you’re claustrophobic, you may feel uncomfortable while in the MRI machine. Tell your doctor about this so they can prescribe anti-anxiety medications. In some cases, you can also be sedated during the scan. It might not be safe to drive afterward if you’ve been sedated. In that case, be sure to arrange for a ride home after the procedure.
An MRI machine looks like a large metal-and-plastic doughnut with a bench that slowly glides you into the center of the opening. You’ll be completely safe in and around the machine if you’ve followed your doctor’s instructions and removed all metal. The entire process can take from 30 to 90 minutes.
If contrast dye will be used, a nurse or doctor will inject the contrast dye through a tube inserted into one of your veins. In some cases, you may need to wait up to an hour for the dye to work its way through your bloodstream and into your spine.
The MRI technician will have you lie on the bench, either on your back, side, or stomach. You may receive a pillow or blanket if you have trouble lying on the bench. The technician will control the movement of the bench from another room. They’ll be able to communicate with you through a speaker in the machine.
The machine will make some loud humming and thumping noises as it takes images. Many hospitals offer earplugs, while others have televisions or headphones for music to help you pass the time.
As the images are being taken, the technician will ask you to hold your breath for a few seconds. You won’t feel anything during the test.
After the test, you’re free to go about your day. However, if you took sedatives before the procedure, you shouldn’t drive.
If your MRI images were projected onto film, it might take a few hours for the film to develop. It will also take some time for your doctor to review the images and interpret the results. More modern machines display images on a computer so your doctor can view them quickly.
It can take up to a week or more to receive all results from your MRI. When the results are available, your doctor will call you to review them and discuss the next steps in your treatment.